Rotor vane



July 8, 1969 P. A. BIEK ETAL ROTOR VANE Filed Oct. 5, 1966 INVENTORS.PAUL A. BIEK MARTIN D HOZA United States Patent 3,453,936 ROTOR VANEPaul A. Biek and Martin D. Hoza, Houston, Tex., assignors to G. W.Murphy Industries, Inc., Houston, Tex., a corporation of Texas FiledOct. 3, 1966, Ser. No. 583,787 Int. Cl. F01c 1/00, 13/02, 21/12 US. Cl.91121 3 Claims ABSTRACT OF THE DISCLOSURE Air operated motors for use inportable tools, such as grinders, drills, fastening tools, and the likehave been long known. Motors of this type are generally provided with acylinder mounted within and spaced apart from the walls of a housing todefine a fluid exhaust chamber. The cylinder is hollow and formed withfluid inlet and exhaust ports, while a rotor, having a plurality ofradially movable vanes, is supported for rotation within the cylinder.The rotor vanes are movable under fluid pressure and contact thecylinder wall to provide motive power in response to pressure beingexerted upon them. Prior art motors of the type generally described aretaught by the following US. patents: 1,942,784 to F. D. Terrill, 600,343to Collins, 1,884,584 to Robert E. Cross, 2,159,- 232 to Shaft,2,222,689 to Schottde, and 2,337,897 to Gaimerson.

When air-operated motors of the type aforementioned are utilized influid powered grinding tools, buffing tools and the like, considerablewear takes place on the rotor vanes, and in fact vane replacement is theprimary cause of repairs to these motors. Grinding tools and the likeare differentiated from other tools employing this same general type ofmotor in that grinders are not provided with clutches and when operated,run for relatively long periods of time, as opposed to the intermittentrunning periods for drills and fastening tools; for these latter toolsthe primary cause of tool breakdown results from clutch and transmissionbreakdown as opposed to rotor vane deterioration. In operating,considerable heat will be generated by the vane of the motor whichcauses excessive wear. This undesirable heating acceleratesdeterioration of the rotor vanes in two ways, as follows: it reduces thelubricating qualities of lubricants located between the vanes and thecylinder wall, and it tends to decompose the vane material.

It was found that, in addition to heating and the consequential problemof heat dissipation, motors constructed in accordance with the prior artteachings were ineflicient in operation when applied to grinding tools.The reason for the foregoing appears to be that the pressure forcesexerted on the rotor vanes by the operating fluid, and the centrifugalforces generated by rotation of the rotor were not optimumly distributedover the vanes. Such force distribution patterns results in decreasedvane life, and further it requires that the vanes be constructed withsloped side walls in order that they not frictionally engage thecylinder heads during use.

Finally, it was determined that motors when constructed in accordancewith the teachings of the prior art and incorporated into grinderstended to accumulate with in their cylinders a quantity of foreignmatter that increased uneven deterioration of the rotor vanes. Thisforeign matter usually comes from two sources as follows: it is composedof particles entrained in the operating fluid and trapped in thecylinder; and it is composed of particles produced by vane wear andlikewise trapped in the motor cylinder.

Therefore it is a primary object of this invention to provide a new andimproved fluid operated motor for portable grinding tools and the like,that causes the rotor vanes to wear evenly.

It is another object of this invention to provide a new and improvedcylinder for air operated motors.

It is the further object of this invention to provide a novel motor fora portable grinding tool that utilizes the operating fluid in such amanner as to provide eflicient cooling of the motor parts, to sweepforeign particles out of the motor cylinder, and to optimumly distributepressure against centrifugal forces on the rotor vanes.

These and other objects of this invention will become apparent upon astudy of the hereinafter described embodiment of the invention taken inconjunction with the drawings, in which:

FIGURE 1 is a side sectional view, having parts broken away of a powertool incorporating the fluid pressure motor of the present invention;

FIGURE 2 is a sectional view the line 2-2 of FIGURE 1;

FIGURE 3 is a perspective view of a motor cylinder used in the toolshown in FIGURE 1;

FIGURE 4 is a plan view of a rotor vane as used in a pricpr art motorshowing the deterioration of the vane; an

FIGURE 5 is a view of a rotor vane showing the uniform wear achieved bythe motor of the present invention.

A typical grinding tool constructed in accordance with the teaching ofthis invention is shown in FIGURES l and 2 of the drawings, wherein amotor housing 10 is provided with a chamber 12 having a motor assembly14 mounted therein.

The motor assembly comprises a cylinder 16, rigidly supported between apair of cylinder heads 18 and 20. The cylinder heads have mountedtherein and support a pair of ball bearing housings 22 and 24respectively, 'WhlCh rotatably support the usual ball bearings. A rotor26 having a pair of projecting shaft ends 28 and 29 is mounted forrotation in the cylinder with the shaft ends belng journaled within thebearing housings. The rotor is provided with a plurality of pistonblades or vanes 30, slidably mounted in radiating slots 32. The rotorshaft end 29 is formed with gear teeth 34 which engage a plurahty ofidler gears 36 that constitute part of the usual and customarytransmission assembly for driving a grinding tool or the like.

Prior art motors utilized for grinding tools and the like are providedwith a motor cylinder having a plurality of ports communicating with alongitudinally extending fluid entry or fill bore, such as the bore 38shown in the cylinder 16. The fluid entry ports are usuallylongitudinally spaced apart along the fill bore. The cylindrical bore 38communicates with a fluid-fill cavity 40 located in the rear or handleend of the motor housing 10. The fill cavity communicates with the usualthrottle and throttle control assembly which is connected to a source ofhigh pressure air or other operating fluid. The fill bore 38 alsocommunicates with a pair of kickout ports 42 and 44 located in thecylinder heads 18 and 20 respectively. The kickout ports cooperate withfill cavities in the rotor slots 32 and are utilized for the purpose ofinjecting air or other fluid into the cavities to thereby of the motortaken along force the vanes 30 into contact with the inside wall of thecylinder 16.

The prior art cylinders have the same general Wall construction andgeometrical configuration as the cylinder 16. They are usually providedwith a plurality of exhaust ports, which ports are symmetrically locatedrelative to the cylinders fluid entry ports. The exhaust ports arenormally circumferentially displaced from the entry ports in order thatmotive power fluid will flow in a clockwise direction within thecylinder, expand and thereby exert pressure on the rotor vanes for aspecified number of degrees of rotation per revolution, after which thefluid is exhausted.

In directing the power fluid to flow circumferentially the rotor vanesof the prior art have to be provided with sloped edges '52 as shown inFIGURE 4 of the drawings. The rotor vanes employed in prior art motorshave their edges angled by a specific angle A in order that as theybecame unbalanced by the deterioration represented by the unequal sidesB and B they would not frictionally engage the cylinder heads 18 and 20.When a cylinder constructed in accordance with this invention isemployed in the motor, the rotor vanes do not have to be provided withangled edges as shown in angles A in FIGURE 4 or angles C in FIGURE 5.

The cylinder 16 of the present invention, FIGURE 3, is designed so as tomake efiicient use of the motive power fluid to overcome theobjectionable features of the prior art motors mentioned infra. Such acylinder is provided with a plurality of fluid entry ports 46 locatedeither forwardly or rearwardly of the cylinder shown in FIGURES 1 and 3,which ports communicate with the fill bore 38. A plurality of exhaustports 48 and 50 are grouped together and longitudinally andcircumferentially displaced from the fluid entry ports. Power fluid istherefore constrained to travel a longitudinal and circumferential pathwithin the cylinder; it expands and exerts turning pressure on the rotorvanes. The motor casing 10 may also be provided with a plurality ofgrouped together exhaust ports 56, which may be laterally andcircumferentially displaced relative to the cylinder exhaust ports 48and 50. In this manner, motive power fluid exhausted from the cylinder16 circulates through an annular passageway 58 created between theoutside wall of the cylinder 16 and the inside wall of the motor casing10, and it may also be made to travel a circumferential and longitudinalpath from the ports 48 and 50 to the ports 56 where it is exhausted tothe atmosphere.

In operation, motive power fluid is directed into the fill cavity 40 byoperation of a throttling valve controlled by a valve operator 60. Fluidis thereby forced into the fill bore 38, the entry ports 46, and thekickout ports 42. Under pressure, the fluid expands within the cylinderand it flows from the forward end of the cylinder rearwardly and in aclockwise direction around the cylinder to the exhaust ports 48 and 50.After being exhausted from the cylinder, the fluid then flows in acounterclockwise direction and forwardly towards the motor casingexhaust ports 56. In this manner, the flow of air is such as tooptimumly distribute forces on the vanes 30, and at the same time toefliciently use the fluid as a coolant for the purpose of minimizingwear. For this latter purpose it is to be noted that with a motorcylinder constructed in accordance with this invention the operatingfluid always has a lower temperature than the motor parts. The fluid isswept along the surfaces of the cylinder, rotor and vanes and thus isable to maximize its cooling effect on these surfaces and at the sametime the fluid is swept circumferentially within and without thecylinder and thus achieves, in addition, whatever cooling effect devicesthe prior art achieved. Since the flow of fluid is in a constantdirection at all times, particles that might have been trapped withinthe cylinder to cause additional uneven wear on the rotor vanes areconstantly swept in one direction and therefore effectively moved out ofthe cylinder and the motor casing. As shown in FIGURE 5 of the drawings,the wear on the rotor vanes utilized in a motor cylinder of the typetaught by this invention is even on both ends.

Although a specific embodiment of our invention has been shown anddescribed, applicants do not intend to be limited thereby. Alternativeconstructions for the cylinder and placement of inlet and exhaust portswill form a study of this specification occur to those skilled in thisart. For example in some cases it may only be desirable to group theinlet ports and the motor casing exhaust ports to achieve the describedflow pattern outside of the motor cylinder. Alternatively the inletports and cylinder exhaust ports may be grouped and displaced asdescribed whereas the motor casing exhaust ports may be distributed asopposed to grouped.

Having described our invention, we claim:

1. In a pressure fluid operated motor for a grinding tool including amotor housing and a rotor having a plurality of radially movable vanemembers mounted therein, the improvement which comprises:

a motor cylinder rigidly supported within said motor housing and spacedtherefrom to define therewith an annular chamber;

said motor housing having a plurality of exhaust ports communicatingwith said annular chamber;

said motor cylinder being provided with a longitudinally extending fluidentry bore and a longitudinally extending cylindrical bore, said rotorbeing mounted for rotation Within said last named bore;

said motor cylinder formed in its cylindrical portion with a pluralityof grouped fluid entry ports, said ports communicating wtih saidlongitudinally extending fluid entry port and said bore; and

said motor cylinder being provided in its cylindrical portion with aplurality of grouped fluid exhaust ports longitudinally andcircumferentially displaced from said grouped fluid entry ports andcommunicating with said rotor bore and said annular chamher.

2. A pressure fluid operated motor according to claim 1 wherein saidmotor housing exhaust ports are grouped together and are longitudinallyand laterally displaced relative to said fluid entry ports.

3. A pressure fluid operated motor according to claim 1 wherein saidplurality of cylinder fluid exhaust ports are grouped together and arecircumferentially and longitudinally displaced from said cylinder fluidentry ports; and wherein said motor housing fluid exhaust ports aregrouped together and are longitudinally and laterally displaced fromsaid group of cylinder exhaust ports.

References Cited UNITED STATES PATENTS 2,857,143 10/1958 Kroeckel et al.91-121 X 3,190,183 6/1965 Walker et al. 91-121 X 3,307,454 3/1967Larsson 91-121 3,376,825 4/1968 Burnett 91-140 X 1,147,238 7/1915 Hauer91-121 X 1,805,023 5/1931 Springsteen 91-140 X 3,241,457 3/1966 Reed91-138 X 2,159,232 5/1939 Shaif 91-138 X 2,570,009 10/1951 Schmid 91-135X 2,980,078 4/1961 Conover 91-138 3,238,848 3/1966 Bent 91-138 EVERETTEA. POWELL, ]r., Primary Examiner.

U.S. Cl. X.R. 91-135

